The present invention relates to a horizontal perforation forming apparatus attached to a folder of a web rotary press to form horizontal perforations extending in a widthwise direction of a traveling web.
A folder is attached to a web rotary press to fold a printed web in its widthwise or longitudinal direction. A horizontal perforation forming apparatus is arranged in the folder to form horizontal perforations extending in the widthwise direction of the web in a perspective folding portion so as to facilitate a subsequent folding operation.
FIG. 16 is a schematic side view of a conventional horizontal perforation forming apparatus of this type. This apparatus will be described with reference to FIG. 16. A horizontal perforation forming apparatus 2, upper and lower nipping rollers 3 and 4, and a rubber roller 5 and a press roller 6 which are respectively in rolling contact with the nipping rollers 3 and 4 are arranged in the traveling path of a web 1 which is traveling between a former (not shown) for folding the printed web in the widthwise direction and a folding cylinder (not shown) for folding the printed web in the longitudinal direction. In the horizontal perforation forming apparatus 2, a perforation cylinder 7 and its mating cylinder 8 are spaced apart from each other by a small gap. A perforation blade case 14 is fixed in a perforation blade groove 7a formed in the axial direction of the perforation cylinder 7. The perforation blade case 14 includes a perforation blade base 9 having a length corresponding to a generator of the perforation cylinder 7, a press plate 10 and a shim 11 which surround the perforation blade base 9, a paper holder 12 dovetailed with the perforation blade base 9, and an elongated plate-like perforation blade 13 held by the central perforation blade groove. The distal end of the perforation blade 13 extends outward from the paper holder 12. An elongated perforation blade seat 15 is fixed in a perforation blade receiving groove 8a extending in the axial direction of the mating cylinder 8. The cylinders 7 and 8, the nipping rollers 3 and 4, and the like are driven from folding paper cylinders through gears in directions indicated by arrows.
With the above structure, the web 1 conveyed upon printing is fed out by the upper nipping roller 3 and is guided to a gap between the cylinders 7 and 8. When the web 1 has passed between the cylinders 7 and 8, it is guided to the lower nipping roller 4 by the folding paper cylinders. In this case, during passing of the web 1 between the cylinders 7 and 8, horizontal perforations are formed in the web 1 by the perforation blade 13 every predetermined interval corresponding to the circumferential length of the cylinder 7 or 8, i.e., every perspective folding position.
In this horizontal perforation forming apparatus, if a gap between the paper holder 12 and the perforation blade seat 15 is not appropriate when they oppose each other, perforations are excessively formed and the web is torn during folding. Alternatively, when perforations are not satisfactory, predetermined folding precision cannot be assured. Therefore, this gap between the paper holder 12 and the perforation blade seat 15 must be appropriately determined. In a conventional perforation forming apparatus, when the distal end of the perforation blade 13 is worn and an extension amount from the paper holder 12 is reduced, when the thickness of printed matters is changed, or when the strength of the perforation portion is changed due to influences of printing conditions (e.g., printing dampening water, an ink, and an image pattern), a drying temperature, an ambient temperature, and paper quality, the perforation blade case 14 as a whole must be removed, and the shim 11 is replaced with a new one or the extension amount of the perforation blade 13 is adjusted. In addition, when printing matters are changed to ones without requiring horizontal perforations, the perforation blade case 14 as a whole is removed, and a balance weight is mounted in place of the perforation blade case 14 so as to prevent unbalance.
In this conventional horizontal perforation forming apparatus described above, the extension amount of the perforation blade 13 must be adjusted. In addition, every time the printed matters are changed to ones which do not require horizontal perforations, the printing press must be stopped or the perforation blade case 14 as a whole must be removed, thus requiring much labor and a time-consuming operation, degrading operation efficiency of the press and the productivity. As the perforation blade case 14 is frequently removed, its fastening bolts are damaged or loosened, or an operator may forget to tighten these bolts. If this occurs, the perforation blade 13 may accidentally be displaced due to centrifugal force from the perforation cylinder 7 rotating at high speed, and an accident may occur. In addition, when the above operations are not properly performed, the web may be torn, and folding precision may be degraded.